Host ID.

Ben Kaduk minimarmot at
Sun Apr 8 23:03:05 UTC 2007

On 4/8/07, Robert Watson <rwatson at> wrote:
> Yes, one of the nice properties of FreeBSD -- as opposed to, say, Windows, is
> that it's trivial to install a hundred boxes by dropping the same image onto
> all of them and configuring host-specific parameters using DHCP.  But there is
> a tricky tension here: the notion of a persisting host ID is very useful, in
> the a similar way to the way in which a persisting SSH host key is useful.
> If we're going to adopt a host ID model, we may want to make generation and
> configuration of the host ID conditional on an explicit variable in rc.conf
> (i.e., hostid_enable="YES" which causes it to be generated the first time and
> loaded future times, similar to SSH keys), and make it very easy to force a
> regen.  That way, you can image the boxes with the rc.conf setting set, but
> they don't generate host IDs until they boot the first time.
> Robert N M Watson
> Computer Laboratory
> University of Cambridge

I like this proposal a lot -- FreeBSD is very flexible, and people can and
will use any mechanism available to make their lives simpler; this can
call for some very creative installation mechanisms.  Robert's proposal
is the most general one I've seen (well, it's orthogonal to a lot of
this thread).

Also, it allows for the paranoid or highly-secure types to change their hostid
(or prevent it from being generated in the first place) -- I have not
yet decided
if I would maintain a local diff to block a unique ID from my systems.

-Ben Kaduk

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